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Pd-Catalyzed Intermolecular Amidation of Aryl Halides: The Discovery that Xantphos Can Be Trans-Chelating in a Palladium Complex

Jingjun Yin and Stephen L. Buchwald*

*Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Email: sbuchwalmit.edu

J. Yin, S. L. Buchwald, J. Am. Chem. Soc., 2002, 124, 6043-6048.

DOI: 10.1021/ja012610k


Abstract

The Xantphos/Pd-catalyzed intermolecular coupling of aryl halides and amides displays good functional group compatibility, and the desired C-N bond forming process proceeds in good to excellent yields. The arylation of sulfonamides, oxazolidinones, and ureas was found to be highly dependent on reaction concentrations and catalyst loadings.

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Details

The document discusses the development of a general method for the intermolecular coupling of aryl halides and amides using a Xantphos/Pd catalyst. This system shows good functional group compatibility and achieves the desired C-N bond formation in good to excellent yields with 1-4 mol % of the Pd catalyst. The method also extends to the arylation of sulfonamides, oxazolidinones, and ureas. The efficiency of these transformations depends on reaction concentrations and catalyst loadings. A Pd complex, (Xantphos)Pd(4-cyanophenyl)(Br) (II), was prepared and found to be an active catalyst for the coupling of 4-bromobenzonitrile and benzamide. X-ray crystallography revealed a rare trans-chelating bisphosphine-Pd(II) structure with a large bite angle of 150.7°. The study highlights the importance of careful control of catalyst loading and reaction concentration for successful amidation of less reactive substrates. The method offers a broad substrate scope and good functional group compatibility, making it a significant advancement in Pd-catalyzed C-N bond-forming reactions.


Pd-Catalyzed Amidations of Aryl Chlorides Using Monodentate Biaryl Phosphine Ligands: A Kinetic, Computational, and Synthetic Investigation

T. Ikawa, T. E. Barder, M. R. Biscoe, S. L. Buchwald, J. Am. Chem. Soc., 2007, 129, 13001-13007.


Key Words

Amidation


ID: J48-Y2002-1130